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Found 345 Resources

Crosby Gas Engine Indicator

National Museum of American History
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 6163. It consists of a small steel piston (1/8 inch); a vented brass cylinder; an internal, double wound spring, which can be changed; a small drum with a spiral spring and a single record; and a brass stylus. Accompanying the indicator is a box with fourteen springs, small tools, and an extra piston with top stem.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

McAvoy’s Patent Model of a Heat Regulator for Hot Water Apparatus - ca 1869

National Museum of American History
This model was filed with the application to the U.S. Patent Office for Patent Number 93,104 issued to Hugh L. McAvoy of Baltimore, Maryland on July 27, 1869. His patent was for a new and improved mechanism for automatically regulating the fire of a boiler for hot water heating or other purposes . Although such regulators then existed, he claimed that his was the first that was designed to be independent of the actual water being heated, thereby allowing flexibility in design. To monitor the temperature of the water being heated he provided for a compartment separate from the boiler but which would be heated to the same temperature as the water in the boiler. This compartment was partially filled with water with a column of air above it. A pipe extended from near the bottom of this compartment and exited through a hole at the top where it was carried to a shallow reservoir containing a float. The reservoir and pipe were filled with water which held the float at an altitude proportional to the pressure of the sealed air in the regulator chamber. As the water increased in temperature, the air pressure increased thereby forcing more water up the pipe which raised the float. The float was attached via a rod to a lever which rotated vertically around a fixed pin in such a way as to raise one end of the lever while lowering the other. A chain at one end of the lever was connected to the draft door of the boiler. The chain at the other end was attached to the fuel door. As temperature increased the first action was for the chain on the draft door to lower thereby slowing the fire. If temperature continued to rise the float rod would force the other end of the lever to raise the fuel door thus rapidly cooling the fire by introduction of cold air to the fire. As the boiler water temperature subsided the float would descend until equilibrium would be found at the desired temperature. This control point was set by adjusting the lengths of the two chains. Research of available trade literature and other sources has not revealed any commercial product that may have made use of this invention by Mr. McAvoy. He held many other patents in the areas of heating, carburetion, firefighting, lighting, oyster canning, air brakes, and refrigeration.

The model is constructed of unpainted tinplate and in its original form modeled the key elements of McAvoy’s regulator design: the fire pit and fire door, fuel door, boiler chamber, regulator chamber with associated pipes, float, and the fulcrum and chains that operated the fire and fuel doors. In its present condition as shown in the image, the float, fulcrum and chains are not installed. Nor is the fuel door present on the model. Diagrams showing the complete design can be found in the patent document online (/www.USPTO.gov/patents/process/search/index.jsp).

Lamb’s Patent Model of a Rotary Steam Engine – ca 1865

National Museum of American History
This model was filed with the application to the U.S. Patent Office for Patent Number 51,389 issued to George A. Lamb of Washington, DC on December 5, 1865. Mr. Lamb’s patent was for a rotary steam engine. The engine design is similar to that of a water wheel. A jet of pressurized steam applied force to the faces of the buckets mounted on the circumference of the wheel. The steam was fed via a tube to a cap mounted at the top of the wheel. Mr. Lamb claimed that his design had the advantage of sealing the gaps between this cap and the buckets on the wheel. The inside of the cap had grooves that fit around the rim of the wheel. Thin strips of flexible metal within the grooves maintained contact with the edge of the wheel and provided a steam seal.

Mr. Lamb and other inventors such as Samuel Harris were active around the same time producing similar designs they described as rotary steam engines. They could be considered early version of the impulse type of steam turbine. Such a turbine was first suggested ca 1629 by Giovanni Branca, an Italian chemist. The invention in 1884 of modern steam turbines is attributed to Sir Charles Parsons.

The model as shown in the image illustrates all of the key elements of the patent. It is constructed of wood and brass and mounted on a wooden base. Diagrams showing the complete design can be found in the patent document online (/www.USPTO.gov).

Ashcroft-Tabor Steam Engine Indicator

National Museum of American History
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 1114. It consists of a brass piston with four grooves; a vented brass cylinder; an internal, single wound spring, which can be changed; a large drum with a coil spring and a single record; and a short pencil lead for stylus. Accompanying the indicator is a box with one turn cock, three small wrenches, and a screw driver. The wooden knob to adjust the pencil pressure is missing.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Manographe Indicator

National Museum of American History
This manographe, or indicator, was purchased by Professor W. H. Kenerson around 1907. He used it in making tests of the Brayton Oil Engine, National Museum of American History catalog number 313.703, at Brown University.

A pivoted mirror reflects a beam of light to a photosensitive plate or paper. Changes in pressure in the engine cylinder cause the mirror to oscillate up and down; a pin and eccentric actuated by a flexible shaft connected to the engine shaft cause the mirror to oscillate from side to side.

The indicator is housed in a wooden box that is 5 inches by 6 inches by 14 inches, with a brass pipe fitting and gear box at one end. The opposite end is open to receive a plate holder of a ground glass. A T-shaped tube lets light into one side, and an adjustable prism inside directs the light to the mirror. The flexible shaft is 32 inches long and covered with black fabric. Four plate holders, one ground glass, a steel petcock and a tapered hollow steel plug are included with the instrument. It is marked “Manographe Hospitalier-Carpentier, Brevete, S G D G, J. Carpentier, Paris.”

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Ericsson Hot-Air Engine, Patent Model

National Museum of American History
This model was filed with the application to the U.S. Patent Office for Patent Number 226,052 issued to John Ericsson of New York, New York on March 30, 1880. The patent was for an improvement in air engines.

In this type of engine a charge of air is repeatedly heated and cooled as it is transferred from one end to the other of a single cylinder. One end of the cylinder is surrounded by a furnace, the other end of is water jacketed. The air expands and contracts beneath a work piston that travels through a short stroke near the upper end of the cylinder. The air is displaced from end to end of the cylinder at the proper time by a large loosely fitting transfer piston independently connected to the crankshaft.

Mr. Ericsson claimed his design improved the method of connecting the short stroke of the work piston so as to magnify the length of its stroke at the crankshaft. This also produced a longer stroke for the exchange piston in order to properly time its movement. He also made provisions for a water pump that was operated by the engine. It circulated water into the jacket surrounding the engine’s cylinder in order to more rapidly cool the hot air in the upper part of the cylinder.

Mr. Ericsson was a prolific inventor; his inventions included many types of steam engines and associated apparatus as well as hot air engines. He was the designer of the USS Monitor for the North during the Civil War, and that vessel included one of his then new marine steam engine designs.

The patent model is shown in the image. It is made of brass, steel and wood. All of the key elements of the patent are illustrated by the model including the crank mechanism and the water pump. The upper cylinder is cut away to illustrate the motion of the two pistons. Diagrams showing the complete design can be found in the patent document online (/www.USPTO.gov).

Take a 3D Tour Through Frank Lloyd Wright's Taliesin West

Smithsonian Magazine

As he aged, architect Frank Lloyd Wright became a snowbird. He’d spend part of the year at his beloved Taliesin home, studio and architecture school in Spring Green, Wisconsin, and starting in 1937, wintered at Taliesin West outside Scottsdale, Arizona. Recently, the Frank Lloyd Wright Foundation teamed up with the Swiss optics company Leica to create a detailed 3D scan of Taliesin West, which allows people around the world to explore the architect’s constantly evolving property.

According to a press release, the Foundation wanted high resolution, 3D digital scans for several reasons. First, it understands that many people simply can’t visit the desert property in person, though over 100,000 per year do make the pilgrimage. And Wright’s narrow, tiered layout makes the property almost impossible to access for visitors with mobility issues. So a scan is the next best thing.

Secondly, reports Anne Quito at Quartz, the Foundation wanted to know more about the property. According to a video about the scan, the property was a laboratory for Wright where he tried out new ideas. He often made design decisions on the fly or modified parts of the buildings while they were being constructed making rough sketches on butcher paper. Because of that, there are no complete diagrams or blueprints for the Foundation to rely on when studying the house. Having the scans, which can be distilled into 2D blueprints and other reference materials, will help the Foundation understand and properly conserve the aging property. “Taliesin West is an extremely complicated building,” Fred Prozzillo, vice president of preservation tells Quito. “Everything is handmade, everything is custom, everything is designed with the environment.”

To capture the intricacies of the national landmark, Leica Geosystems used their new 3D imaging system, the Leica BLK360. The scanner not only takes 360-degree images of the property, it also creates a 3D point cloud, which uses lasers to take extremely accurate dimensions of walls, windows, even furniture and trees, down to an accuracy of just six millimeters. That data can then be imported into architectural and building software to help make decisions about conservation and restoration. The immersive 3D model was created by Matterport, a 3D media company.

The virtual tour allows users to visit each room of Taliesin West and examine things like light fixtures and furniture, most of it designed by the architect himself. It also allows visitors to get up close with the desert rocks and other natural materials used in construction and view the surrounding Sonoran desert.

Foundation CEO Stuart Graff tells Quito that Wright probably would have been excited to use the new technology if he was still around. “Experimentation, innovation is at the heart of Frank Lloyd Wright’s 70-year career,” he says. “‘What’s possible’ is the credo of his work.”

Graff also says that disseminating Wright’s ideas and legacy are more important than ever. Wright is often cited as being the first “green architect,” though he would not have used that term. His idea of harmonizing his designs with their surroundings, instead of trying to overpower or dominate the landscape, is a principle of sustainability. He was also an advocate of using local materials in construction and using local plants for landscaping. “More than an architect of buildings, Wright was an architect of ideas whose time has come now with great urgency as we face great challenges to sustainability,” Graff says.

According to the press release, Taliesin in Wisconsin will also soon be scanned and available online as well.

Trill Steam Engine Indicator

National Museum of American History
The Trill Indicator Co. manufactured this steam engine indicator, serial number 27. It consists of a brass piston; a brass cylinder, which is open at top; an external, double wound spring, which can be changed; a large drum with a spiral spring and a single record; and a short lead pencil as stylus. Accompanying the indicator is a box with six springs, two drum springs, two wrenches, and three turn cocks.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Hospitalier-Carpentier Manographe

National Museum of American History
This manographe, or indicator, was purchased by Professor W. H. Kenerson around 1907. He used it in making tests of the Brayton Oil Engine, National Museum of American History catalog number 313.703, at Brown University.

A pivoted mirror reflects a beam of light to a photosensitive plate or paper. Changes in pressure in the engine cylinder cause the mirror to oscillate up and down; a pin and eccentric actuated by a flexible shaft connected to the engine shaft cause the mirror to oscillate from side to side.

The indicator is housed in a wooden box that is 5 inches by 6 inches by 14 inches, with a brass pipe fitting and gear box at one end. The opposite end is open to receive a plate holder of a ground glass. A T-shaped tube lets light into one side, and an adjustable prism inside directs the light to the mirror. The flexible shaft is 32 inches long and covered with black fabric. Four plate holders, one ground glass, a steel petcock and a tapered hollow steel plug are included with the instrument. It is marked “Manographe Hospitalier-Carpentier, Brevete, S G D G, J. Carpentier, Paris.”

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Tabor Steam Engine Indicator

National Museum of American History
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 2325. It consists of a brass piston with three grooves; a vented brass cylinder; an internal, single wound spring, which can be changed; a large drum with a coil spring and a single record. The end of the linkage that holds the stylus is missing, as is the pulley. Accompanying the indicator is a box with several springs.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Crosby Steam Engine Indicator

National Museum of American History
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 3309. It consists of a piston, which is stuck inside the cylinder. A brass stylus can record onto a large small drum with a spiral spring and a single record. Accompanying the indicator is a box with twelve springs and a spring wrench.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Bacharach Steam Engine Indicator

National Museum of American History
Bacharach Industrial Instrument Co. manufactured this steam engine indicator. It consists of a large steel piston with three grooves; a vented brass cylinder; an external, double wound spring, which can be changed; an aluminum drum with a small spiral spring and single record; and a small brass stylus. Accompanying the indicator is a box with three springs and some small tools. The pulley and bracket are missing.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Crosby Steam Engine Indicator

National Museum of American History
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 330. It consists of a brass piston with one groove, a vented brass cylinder, an internal, double wound spring which can be changed, and a small drum with a spiral spring and single record. The stylus is missing. Accompanying the indicator is a box with two springs, two turn cocks, a scale, and small tools.

This indicator was made for W. J. Hammer, Chief Inspector of Edison Light Co. There is a nickel-plated name plate on the front marked: “Property of W. J. Hammer, 65 Fifth Ave, New York.”

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Tabor Steam Engine Indicator

National Museum of American History
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 2329. It consists of a steel piston with a guide below the spring; a vented brass cylinder; an internal, single wound spring, which can be changed; a large drum with a coil spring and a single record. The piston, spring, and parts of the linkage are missing.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Ashcroft Tabor Steam Engine Indicator

National Museum of American History
Ashcroft Mfg. Co. of Bridgeport, Connecticut, manufactured this Tabor steam engine indicator, serial number 2839. It consists of a brass piston with four grooves; a brass cylinder with an adjustable sleeve with vents; an internal, single wound spring, which can be changed; a large drum with a coil spring and a single record. It has a short pencil lead at the end for a stylus. Accompanying the indicator is a box with three springs, two turn cocks, an extra drum spring, pencil points, wrench, pad of record paper, a special board for record, and three scales.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Thompson Steam Engine Indicator Patent Model

National Museum of American History
This indicator was made by the American Steam Gauge Co., of Boston. It is marked “J. W. Thompson Pat. August 31, ’75 Pat. June 26, 1883, N. 4302.”

In this indicator the piston rod is hollow and serves only as a guide for the piston. The pencil mechanism is connected to the piston by a very light rod that passes through the piston rod and is attached to the piston with a swivel joint. This permits the use of a very simple and light parallel motion.

The piston is a light cylindrical shell provided with three grooves that collect moisture and steam to lubricate and seal the piston. The inner wall of the cylinder is a liner separate from and secured to the inclosing cylinder only at one end so that it is free to expand and contract with temperature changes, thus avoiding distortion.*

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

*Reference:

This description comes from the 1939 Catalog of the Mechanical Collections of the Division of Engineering United States Museum Bulletin 173 by Frank A. Taylor.

Lippincott Steam Engine Indicator

National Museum of American History
The Lippincott Steam Specialty and Supply Co. manufactured this steam engine indicator, serial number 1380. It consists of a steel piston with two grooves and a bottom guide; a brass cylinder; an internal spring, which is missing; a small drum with a spiral spring and single record. The stylus is missing, but assumed to be a lead pencil point. Accompanying the indicator is a box with four springs, and extra piston, a wrench, reduction pulleys, record cards, and scales.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Crosby Steam Engine Indicator

National Museum of American History
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 1074D. It consists of a steel piston; a vented brass cylinder; an external, double wound spring, which can be changed; a large drum with a spiral spring and a single record; and a brass stylus. Accompanying the indicator is a box with twelve springs and some small tools.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

American Steam Gauge Steam Engine Indicator

National Museum of American History
The American Steam Gauge Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 572. It consists of a brass piston with one groove; a brass cylinder; an internal, single wound spring, which can be changed; a large drum with a coil spring and single record. The stylus is missing. Accompanying the indicator is a box with two small wrenches; a packet of record paper with the title on top of the Taylor Engine Company Time Card; and actual engine records on five sheets.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Lehmann & Michels Gas Engine Indicator

National Museum of American History
Lehmann & Michels manufactured this gas engine indicator in Germany. According to a card inside the box, this style of indicator was invented by Voelcker about 1928. It consists of a steel piston with one groove, a vented brass cylinder; an external, double wound spring, which can be changed; a small aluminum drum and single record. There is an additional device to turn the drum by a steel handle that is driven from the crank or cam shaft. Accompanying the indicator is a box with tools, one spring, extra parts, a pad of paper, and product literature.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.

Wiegand's Patent Model of a Variable Eccentric for a Steam Engine Cut-Off Valve – ca 1857

National Museum of American History
This model was filed with the application to the U.S. Patent Office for Patent Number 18,311 issued to S. Lloyd Wiegand of Philadelphia, Pennsylvania on September 29, 1857. The patent was for an improved mechanism to operate the cut-off valve gear for steam engines.

Wiegand's design provided a means of adjusting the point in the power stroke of the engine’s piston at which high pressure steam being fed to the cylinder was cut off. This was desirable as power was extracted from the expansive force of the steam after the valve closed. This saved fuel by avoiding continuing use of high pressure steam. Wiegand provided a means of adjusting the point of cut-off while the engine was running. This was not new; others such as B. H. Wright and George Corliss had patented devices to do so. Both Wiegand and Wright based their designs on variable eccentrics. In a variable eccentric, the amount of eccentricity, or offset from the shaft center, can be varied by a control mechanism.

The method to accomplish this consisted of an inclined metal slide that varied the amount of eccentricity as a lever was moved causing the slide to move through a slot in the eccentric wheel. Wiegand's claim was that his design for the first time allowed such adjustments to be made regardless of whether the engine was operating in forward or reverse. In the image of the model the lever operating the steam inlet valve would rest upon the top of the eccentric which is the thin cylinder to the right center.

The patent model is constructed of brass and mounted on a hammered brass plate which is mounted on a wooden base. The brass base plate is inscribed “S. Lloyd Wiegand, Philadelphia, PA.” The control lever is shown at the left. The miniature hand crank at the right was intended to demonstrate the movement of the cut-off mechanism. Diagrams showing the complete design of the patent can be found in the patent document online at the United States Patent and Trademark Office website, /www.uspto.gov.

Van Deren’s Patent Model of a Steam Engine– ca 1860

National Museum of American History
This model was filed with the application to the U.S. Patent Office for Patent Number 29,642 issued to G.W. Van Deren of Bigflats, New York on August 14, 1860. The patent was for a steam engine design employing an oscillating piston. Instead of the more common straight cylinder with a piston within, Van Deren employed two pistons within a semi-circular cylinder. The pistons were connected by a curved rod with a pin in the middle for attachment of the connecting rod to the crankshaft. A steam valve above the cylinder admitted and exhausted steam alternatively for one, then the other piston. This caused a rocking motion of the pistons, and the connecting rod imparted rotation to the flywheel via the crank arm. This eliminated the need for crossheads and slides.

The inventor claimed that his design reduced stresses on the engine at the end of each cycle of the pistons and thus allowed operation at higher speeds. He also claimed reduced costs of construction. A search of available material did not reveal any commercial use of Van Deren’s design. He held two additional patents for components of oscillating steam engines.

The patent model is constructed of iron and steel. All of the key elements of the patent are illustrated by the model which demonstrates the engine motion. In the image the steam valve housing is the horizontal cylinder at the top of the model. The inlet is the orange pipe and the exhaust is from the top of the valve housing. The engine’s cylinder containing the pistons is the green semi-circular structure below the steam valve housing. The horizontal steel rod in front is the connecting rod from the pistons to the crankshaft. The valve gear eccentric is shown on the crankshaft on the right with its connected rods and levers to operate the valve. Diagrams showing the complete design of the patent can be found in the patent document online at the United States Patent and Trademark Office website, /www.uspto.gov.

Corliss' Patent Model of a Steam Engine Cut-Off Valve – ca 1851

National Museum of American History
This model was filed with the application to the U.S. Patent Office for Patent Number 8,253 issued to George H. Corliss of Providence, Rhode Island on July 29, 1851. The patent was for an improved cut-off valve gear for steam engines. With this patent Corliss was seeking to improve the durability of such a valve gear and to improve its ability to operate at high speeds.

Corliss' design provided a means of adjusting the point in the power stroke of the engine’s piston at which high pressure steam being fed to the cylinder was cut off. This was desirable as power was extracted from the expansive force of the steam after the valve closed. This saved fuel by avoiding continuous use of high pressure steam.

Corliss' major innovation was that the connections from the steam inlet valve push rods to the valve port cranks were not permanent. The details of his design can be seen in the upper left of the image of the model. Each crank had a "toe" that was engaged by a hook on its respective pushrod. A spring held against the pushrod caused the toe and hook to remain engaged. The worm gear shown on the left of the model allowed adjustment of rods that would move so as to apply pressure to the pushrods overcoming the force of the springs, thereby causing the toe and hook to disengage To assure the steam valve ports closed properly with the hook and toe disengaged, Corliss provided a heavy weight to pull the crank arms down. The weight and its connected rod are shown at the extreme left of the image. Changing the number of turns of the worm gear varied the point in the cycle where the pushrods would disengage. This allowed the timing of cut off to be varied as dictated by the operating conditions of the engine at the time.

Corliss was a prolific inventor of steam technology in the middle 1800s and was the founder of the Corliss Steam Engine Company. His engines were used worldwide, and his designs were adopted by other engine manufacturers.

The patent model is constructed of brass and mahogany. All of the key elements of the patent are illustrated by the model. The image of the rear side of the model shows the steam and exhaust valve operation. Diagrams showing the complete design of the patent can be found in the patent document online at the United States Patent and Trademark Office website, /www.uspto.gov.

Crosby Gas Engine Indicator

National Museum of American History
Crosby Steam Gauge & Valve Co. of Boston, Massachusetts, manufactured this steam engine indicator, serial number 8619. It consists of a steel piston with four grooves, a vented brass cylinder, an internal spring (which is missing), a small drum with a spiral spring and a single record, and a brass stylus. Accompanying the indicator is a box with twelve springs, double wound, and some small tools.

An engine indicator is an instrument for graphically recording the pressure versus piston displacement through an engine stroke cycle. Engineers use the resulting diagram to check the design and performance of the engine.

A mechanical indicator consists of a piston, spring, stylus, and recording system. The gas pressure of the cylinder deflects the piston and pushes against the spring, creating a linear relationship between the gas pressure and the deflection of the piston against the spring. The deflection is recorded by the stylus on a rotating drum that is connected to the piston. Most indicators incorporate a mechanical linkage to amplify the movement of the piston to increase the scale of the record.

When the ratio of the frequency of the pressure variation to the natural frequency of the system is small, then the dynamic deflection is equal to the static deflection. To design a system with a high natural frequency, the mass of the piston, spring, stylus, and mechanical linkage must be small, but the stiffness of the spring must be high. The indicator is subjected to high temperatures and pressures and rapid oscillations, imposing a limitation on the reduction in mass. Too stiff a spring will result in a small displacement of the indicator piston and a record too small to measure with accuracy. Multiplication of the displacement will introduce mechanical ad dynamic errors.

The parameters of the problem for designing an accurate and trouble free recorder are such that there is no easy or simple solution. Studying the variety of indicators in the collection shows how different inventors made different compromises in their designs.
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